The US has a nasty past of funding death squads and paramilitary forces to stifle anti-American attitudes and dissent. But what about the context of the uprisings in the Middle East? We're told that the CIA is helping secular rebels in Syria to fight both the regime and Islamists, giving them training, arms, etc. NATO and various UN members gave aid to Libyan rebels. It's all very select who receives this aid, and there's no doubt some statist agenda behind the help, but is it undesirable for nations such as the US to aid various rebel groups? Or are the rebels receiving said aid too questionable in their agendas as well (instituting a US-friendly state, per example)?
Something else: would it be appropriate (for lack of a better word at the moment) for anarchist rebels/insurrectionists/revolutionaries to accept aid from a foreign state (as unlikely as it is to ever happen)?

While Dot's answer is pretty complete and succinct, I thought I'd add one thing that might help you digest it. Here is an article written by a Syrian anarchist, published on SolFed's (British section of the IWA) website that may facilitate a deeper understanding through application:

a) The author comments on the desperation of the situation and the need for aid, but does not advocate intervention from western (or any other) states, instead they provide contact details for solidarity funds/direct contributions.

b) The author's discussion of the intervention of foreign states in the conflict highlights that all intervention has been, as Dot also noted, exclusively self-interested, and has only made the situation worse.

Ps. I'm not affiliated with SolFed in any way; also, I'm new here so if this would be more appropriate as a 'comment' rather than an 'answer' then please let me know/go ahead and move it.

yea, i wouldn't say this is an answer because the gist of it is to look at the link (vs you paraphrasing or quoting, but also providing link for back up).
so i'd make it a comment, but no biggie in this case. mostly for future reference.
and welcome. :)